Signs of feline eye disease include squinting, pawing or rubbing of the eye, redness of the tissue lining the eyelid, excessive tearing, unequal pupil sizes, a visible third eyelid (a white membrane that fans out from the inner corener of the eye), cloudiness or color changes in the eye, and, of course, blindness.
Eye discharge may appear temporarily if there is an eye wound or a foreign body is lodged there. The eye will then automatically secrete an unusually large amount of tears in an attempt to cleanse itself. However, if the discharge is constant, this indicates and abnormal condition. A back-up of wastes in the body may cause the eyes and/or ears to run as the system tries to rid itself of toxins through any door it can fnd. A diet high in chemicals (preservatives and food additives) or a poorly balanced diet, such as an all-meat diet, can be the cause, as can leaving food available between meals, which slows the metabolism and causes wastes to back up. An infection in an eye can spread from dirty teeth or from upper respiratory problems. Conversely, infected tear ducts can spread infection into the mouth, nose, ears, or upper respiratory tract.
By far the most common cause of chronic eye discharge is blocked and/or malformed tear ducts. Persian cats are especially plagued with eye problems because of in-breeding to produce the congenital deformity of a very flat face (called the "peke-face"). The flat, straight nose of the very inbred Siamese can also produce the same problem because, as with the Persian's face, there is not enough room for normal tear ducts in the deformed skull structure. Many cats with eye problems come out from catteries where they are inbred to produce the specific facial structure that predisposes them to have this problem.
A cataract is a white cloudiness occurring in the clear lens of the eye where light and images are transmitted and focused. Cataract is most frequently found in old or diabetic animals, but it is sometimes seen in younger cat s as well. It is often difficult to trace the cause, but any one of several dietary deficiencies have produced cataracts in laboratory animals. A vitamin B-2 deficiency can produce oily skin and lashes as well as cataracts. A cholesterol problem will clog all of the blood vessels, including the small capillaries feeding the eye, and cataracts can result. A diet lacking the amino acids histidine, phenylalanine, and others has produced cataracts. A cat forced to survive on a vegetarian diet will always go blind from lack of taurine, an amino acid found only in animal flesh; cats cannot manufacture their own taurine as humans can. Certain types of cataracts have been produced when vitamin C was lacking. Signs include cloudiness inside the eye behind the pupil; chewing and licking nonfood items such as glue, wires, plastic, bricks, belts, or cat litter.
When a cat's lower eyelid rolls permanently inward (entropion) the lower lashes will rub against the cornea and produce an ulcer that is sometimes visible as a white line from healed "old" ulcers or a crater in the cornea. In some cats, entropion is congenital deformity. In others, it can develop slowly because of repeated inflammation or swelling caused by infection or injuries, washing while teeth are dirty, germ growth in blocked tear ducts, or infections spreading from the nose. When the lower lid swells and shrinks again and again, the tissues become abnormal in shape and can shrivel inward, producing entropion. This condition is easily corrected by surgery but will recur if the underlying cause is not cleared up. Signs include constant tearing and eye discharge of colorless, brown, or white material; frequent blinking; sometimes a white line is visible just under lower lid; lower lashes touching eye.
A corneal ulcer is a minor or deep wound on the surface of the eye itself. The scratch is usually difficult to see, but it causes a runny eye for a day or two, then heals over if the animal is in a state of normal health. If there is any blood in the eye discharge - any at all - the cat should be rushed to the veterinarian for treatment. Blood in an eye wound is always serious and indicates that the very delicate inner eye has been injured and the wound is very deep. Signs include watery eye or eye discharge of yellowe or brown material; closing eye or squinting; bloody discharge - see veterianrian at once.